Peripheral immune checkpoint gene expression as diagnostic biomarkers in idiopathic pulmonary fibrosis
Immune checkpoint biomarkers in IPF
Keywords:
Biomarker, IPF, PD-1, PD-L1, TIM-3, TOLLIPAbstract
Background and aim: Idiopathic pulmonary fibrosis (IPF) is a relatively rare and progressive fibrotic interstitial lung disease with limited annual incidence and poor prognosis. Increasing evidence suggests that immune dysregulation, including altered immune checkpoint and innate regulatory signaling pathways, may contribute to disease pathogenesis. This study aimed to investigate peripheral blood expression levels of PD-1, PD-L1, TIM-3, and TOLLIP genes and to evaluate their diagnostic potential in patients with IPF.
Methods: This case–control study included 20 IPF patients and 20 age-matched healthy controls. Gene expression levels were quantified using real-time quantitative polymerase chain reaction (RT-qPCR) and calculated using the ΔCt method. Diagnostic discrimination was assessed by receiver operating characteristic (ROC) analysis.
Results: PD-L1 (p < 0.001) and TOLLIP (p = 0.002) ΔCt values were significantly higher, indicating reduced relative gene expression. ROC analysis demonstrated strong diagnostic performance for PD-L1 (AUC = 0.883) and TOLLIP (AUC = 0.865). The combined PD-L1 + TOLLIP biomarker panel demonstrated superior diagnostic accuracy (AUC = 0.948). Internal validation using bootstrap resampling confirmed model stability (mean AUC = 0.950; 95% CI: 0.85–1.00).
Conclusions: In conclusion, peripheral blood PD-L1 and TOLLIP expression levels are significantly downregulated in patients with idiopathic pulmonary fibrosis. The combined PD-L1 + TOLLIP biomarker panel demonstrated strong diagnostic discrimination (AUC = 0.948), supporting the potential clinical utility of peripheral immune regulatory gene signatures as minimally invasive biomarkers in IPF. Larger prospective studies are warranted to validate these findings and to explore their potential role in clinical decision-making.
References
1. Raghu G, Remy-Jardin M, Richeldi L, et al. Idiopathic pulmonary fibrosis (an update) and progressive pulmonary fibrosis in adults: an official ATS/ERS/JRS/ALAT clinical practice guideline. Am J Respir Crit Care Med. 2022;205:e18–e47. doi: 10.1164/rccm.202202-0399ST
2. Sgalla G, Iovene B, Calvello M, et al. Idiopathic pulmonary fibrosis: pathogenesis and management. Respir Res. 2018;22;19(1):32. doi: 10.1186/s12931-018-0730-2
3. George PM, Spagnolo P, Kreuter M, et al. Progressive fibrosing interstitial lung disease: clinical uncertainties, consensus recommendations, and research priorities. Lancet Respir Med. 2020;8:925-934. doi: 10.1016/S2213-2600(20)30355-6
4. Shenderov K, Collins SL, Powell JD, et al. Immune dysregulation as a driver of idiopathic pulmonary fibrosis. J Clin Invest. 2021;131:e143226. doi: 10.1172/JCI143226
5. Wynn TA. Cellular and molecular mechanisms of fibrosis. J Pathol. 2008; 214(2):199-210. doi: 10.1002/path.2277
6. Karampitsakos T, Juan-Guardela BM, Tzouvelekis A, et al. Precision medicine advances in idiopathic pulmonary fibrosis. EBioMedicine. 2023; 95:104766. doi: 10.1016/j.ebiom.2023.104766
7. Tan J, Xue Q, Hu X, et al. Inhibitor of PD-1/PD-L1: a new approach may be beneficial for the treatment of idiopathic pulmonary fibrosis. J Transl Med. 2024; 22(1):95. doi: 10.1186/s12967-024-04884-7
8. Geng Y, Liu X, Liang J, et al. PD-L1 on invasive fibroblasts drives fibrosis in a humanized model of idiopathic pulmonary fibrosis. JCI Insight. 2019;4:e125326. doi: 10.1172/jci.insight.125326
9. Guo X, Sunil C, Adeyanju O, et al. PD-L1 mediates lung fibroblast to myofibroblast transition through Smad3 and β-catenin signaling pathways. Sci Rep. 2022;12:3053.doi: 10.1038/s41598-022-07044-3
10. Gao D, Gao W, Zhai Z, et al. Immune mechanisms and novel therapies for idiopathic pulmonary fibrosis. Pharm Sci Adv. 2023;23;2:100030. doi: 10.1016/j.pscia.2023.100030
11. Wang Y, Kuai Q, Gao F, et al. Overexpression of TIM-3 in Macrophages Aggravates Pathogenesis of Pulmonary Fibrosis in Mice. Am J Respir Cell Mol Biol. 2019;61(6):727-736. doi: 10.1165/rcmb.2019-0070OC.
12. Tirelli C, Pesenti C, Miozzo M, et al. The Genetic and Epigenetic Footprint in Idiopathic Pulmonary Fibrosis and Familial Pulmonary Fibrosis: A State-of-the-Art Review. Diagnostics (Basel). 2022 Dec 9;12(12):3107. doi: 10.3390/diagnostics12123107
13. Li X, Goobie GC, Gregory AD, et al. Toll-Interacting Protein in Pulmonary Diseases. Abiding by the Goldilocks Principle. Am J Respir Cell Mol Biol. 2021; 64(5):536-546. doi: 10.1165/rcmb.2020-0470TR
14. Song L, Li K, Chen H, et al. Cell Cross-Talk in Alveolar Microenvironment: From Lung Injury to Fibrosis. Am J Respir Cell Mol Biol. 2024;71(1):30-42. doi: 10.1165/rcmb.2023-0426TR
15. Karampitsakos T, Galaris A, Chrysikos S, et al. Expression of PD-1/PD-L1 axis in mediastinal lymph nodes and lung tissue of human and experimental lung fibrosis indicates a potential therapeutic target for idiopathic pulmonary fibrosis. Respir Res. 2023;14;24(1):279. doi: 10.1186/s12931-023-02551-x
16. Tu J, Xu H, Ma L, et al. Nintedanib enhances the efficacy of PD-L1 blockade by upregulating MHC-I and PD-L1 expression in tumor cells. Theranostics. 2022;1;12(2):747-766. doi: 10.7150/thno.65828
17. Reyfman PA, Walter JM, Joshi N, et al. Single-cell transcriptomic analysis of human lung provides insights into the immune microenvironment of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2019;199(12):1517-1536. doi: 10.1164/rccm.201712-2410OC
18. Jiang A, Liu N, Wang J, et al. The role of PD-1/PD-L1 axis in idiopathic pulmonary fibrosis: Friend or foe? Front Immunol. 2022;5;13:1022228. doi: 10.3389/fimmu.2022.1022228
19. Katayanagi S, Setoguchi Y, Kitagawa S, et al. Alternative Gene Expression by TOLLIP Variant Is Associated With Lung Function in Chronic Hypersensitivity Pneumonitis. Chest. 2022, 161(2):458-469. doi: 10.1016/j.chest.2021.08.052
20. Whalen W, Berger K, Kim JS, et al. TOLLIP SNP and Antimicrobial Treatment Effect in Idiopathic Pulmonary Fibrosis. Am J Respir Crit Care Med. 2024;15;210(4):508-511. doi: 10.1164/rccm.202312-2224LE
21. Kayıkçı A, Alatas F, Alatas IO, Yıldırım H, Ozen H. The role of biomarkers in the diagnosis and treatment follow-up of idiopathic pulmonary fibrosis. Sarcoidosis Vasc Diffuse Lung Dis. 2024;41(2):e2024015. doi: 10.36141/svdld.v41i2.15454
22. Zhai K, Zang D, Yang S. Zhang Y, Niu S, Yu X. Biomarkers for Early Diagnosis of Idiopathic Pulmonary Fibrosis: A Systematic Review. J. Med. Biol. Eng. 2024;44:666–675. doi:10.1007/s40846-024-00909-0
23. d'Alessandro M, Bergantini L, Cameli P, Pieroni M, Refini RM, Sestini P, et al. Serum Concentrations of KL-6 in Patients with IPF and Lung Cancer and Serial Measurements of KL-6 in IPF Patients Treated with Antifibrotic Therapy. Cancers (Basel). 2021;13(4):689. doi: 10.3390/cancers13040689
24. Cerri S, Manzini E, Nori O, et al. Genetic Risk Factors in Idiopathic and Non-Idiopathic Interstitial Lung Disease: Similarities and Differences. Medicina (Kaunas). 2024;60(12):1967. doi: 10.3390/medicina60121967
25. Oldham JM, Huang Y, Bose S, et al. Proteomic Biomarkers of Survival in Idiopathic Pulmonary Fibrosis. Am J Respir Crit Care Med. 2024;1;209(9):1111-1120. doi: 10.1164/rccm.202301-0117OC
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